Academic literature on the topic 'Strain engineering efforts'
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Journal articles on the topic "Strain engineering efforts"
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Dang, Chaoqun, Anliang Lu, Heyi Wang, Hongti Zhang, and Yang Lu. "Diamond semiconductor and elastic strain engineering." Journal of Semiconductors 43, no. 2 (February 1, 2022): 021801. http://dx.doi.org/10.1088/1674-4926/43/2/021801.
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Abstract Diamond, as an ultra-wide bandgap semiconductor, has become a promising candidate for next-generation microelectronics and optoelectronics due to its numerous advantages over conventional semiconductors, including ultrahigh carrier mobility and thermal conductivity, low thermal expansion coefficient, and ultra-high breakdown voltage, etc. Despite these extraordinary properties, diamond also faces various challenges before being practically used in the semiconductor industry. This review begins with a brief summary of previous efforts to model and construct diamond-based high-voltage switching diodes, high-power/high-frequency field-effect transistors, MEMS/NEMS, and devices operating at high temperatures. Following that, we will discuss recent developments to address scalable diamond device applications, emphasizing the synthesis of large-area, high-quality CVD diamond films and difficulties in diamond doping. Lastly, we show potential solutions to modulate diamond’s electronic properties by the “elastic strain engineering” strategy, which sheds light on the future development of diamond-based electronics, photonics and quantum systems.
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Ratnaparkhe, Supriya, and Milind B. Ratnaparkhe. "Advances in Strain Engineering for Improved Bio-fuel Production- a Perspective." Current Metabolomics and Systems Biology 7, no. 1 (September 6, 2020): 1–5. http://dx.doi.org/10.2174/2213235x07999190528085552.
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Bio-fuels are ecologically sustainable alternates of fossil fuel and have attracted interest of research community in the last few decades. Microorganisms such as bacteria, fungi and microalgae have important roles to play at various steps of bio-fuel production. And therefore several efforts such as genetic engineering have been made to improve the performance of these microbes to achieve the desired results. Metabolic engineering of organisms has benefitted immensely from the novel tools and technologies that have recently been developed. Microorganisms have the advantage of smaller and less complex genome and hence are best suitable for genetic manipulations. In this perspective, we briefly review a few interesting studies which represent some recent advances in the field of metabolic engineering of microbes.
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Leem, Juyoung. "A snapshot review on exciton engineering in deformed 2D materials." MRS Advances 5, no. 64 (2020): 3491–506. http://dx.doi.org/10.1557/adv.2020.350.
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AbstractMost optoelectronic characteristics of two-dimensional (2D) materials are associated with excitonic effects. Excitonic effects in 2D material have been intensively investigated, and various efforts to engineer exciton behavior in 2D materials have been reported for advanced nanophotonic and optoelectronic applications. Excitons in 2D semiconductors can be controlled by external stimuli, including mechanical, electrical, thermal, and magnetic stimuli. Mechanical stimuli applied to a 2D material can generate uniform or non-uniform deformation and strain gradient in the 2D lattice, which creates a strain-induced bandgap energy gradient in the 2D material. In an inhomogeneous bandgap energy gradient generated by a non-uniform strain gradient, excitons drift across the energy gradient. Exciton engineering in deformed 2D materials aims to control exciton movement by mechanical strain. In this snapshot review, we focus on exciton engineering in a mechanically deformed 2D material and their potential towards advanced optoelectronic and photonic applications.
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Zhang, Yu, Tsan-Yu Chiu, Jin-Tao Zhang, Shu-Jie Wang, Shu-Wen Wang, Long-Ying Liu, Zhi Ping, et al. "Systematical Engineering of Synthetic Yeast for Enhanced Production of Lycopene." Bioengineering 8, no. 1 (January 19, 2021): 14. http://dx.doi.org/10.3390/bioengineering8010014.
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Synthetic biology allows the re-engineering of biological systems and promotes the development of bioengineering to a whole new level, showing great potential in biomanufacturing. Here, in order to make the heterologous lycopene biosynthesis pathway compatible with the host strain YSy 200, we evolved YSy200 using a unique Synthetic Chromosome Rearrangement and Modification by LoxP-mediated Evolution (SCRaMbLE) system that is built in the Sc2.0 synthetic yeast. By inducing SCRaMbLE, we successfully identified a host strain YSy201 that can be served as a suitable host to maintain the heterologous lycopene biosynthesis pathway. Then, we optimized the lycopene biosynthesis pathway and further integrated into the rDNA arrays of YSy201 to increase its copy number. In combination with culturing condition optimization, we successfully screened out the final yeast strain YSy222, which showed a 129.5-fold increase of lycopene yield in comparison with its parental strain. Our work shows that, the strategy of combining the engineering efforts on both the lycopene biosynthesis pathway and the host strain can improve the compatibility between the heterologous pathway and the host strain, which can further effectively increase the yield of the target product.
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Corley-Lay, Judith B. "Efforts by North Carolina Department of Transportation to Develop Mechanistic Pavement Design System." Transportation Research Record: Journal of the Transportation Research Board 1539, no. 1 (January 1996): 18–24. http://dx.doi.org/10.1177/0361198196153900103.
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A first generation mechanistic empirical pavement design procedure was developed using falling weight deflectometer deflections taken over a 3-year period at 16 test sections in Siler City, North Carolina. Information available for use in developing the procedure included deflection data, surface and air temperature, coring thicknesses at each test location, pavement performance records regarding rate of cracking, and traffic records. Jung's method, based on the curvature of the deflection bowl, was used to calculate strain at the bottom of the asphalt layer as a measure of fatigue. This calculated strain was used to obtain a calculated number of load repetitions to failure. Comparision of actual loads to failure with calculated loads to failure resulted in a table of shift factors by pavement type.
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Nah, Ji-Hye, Hye-Jin Kim, Han-Na Lee, Mi-Jin Lee, Si-Sun Choi, and Eung-Soo Kim. "Identification and Biotechnological Application of Novel Regulatory Genes Involved inStreptomycesPolyketide Overproduction through Reverse Engineering Strategy." BioMed Research International 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/549737.
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Polyketide belongs to a family of abundant natural products typically produced by the filamentous soil bacteriaStreptomyces. Similar to the biosynthesis of most secondary metabolites produced in theStreptomycesspecies, polyketide compounds are synthesized through tight regulatory networks in the cell, and thus extremely low levels of polyketides are typically observed in wild-type strains. Although manyStreptomycespolyketides and their derivatives have potential to be used as clinically important pharmaceutical drugs, traditional strain improvement strategies such as random recursive mutagenesis have long been practiced with little understanding of the molecular basis underlying enhanced polyketide production. Recently, identifying, understanding, and applying a novel polyketide regulatory system identified from various Omics approaches, has become an important tool for rationalStreptomycesstrain improvement. In this paper, DNA microarray-driven reverse engineering efforts for improving titers of polyketides are briefly summarized, primarily focusing on our recent results of identification and application of novel global regulatory genes such aswblA, SCO1712, and SCO5426 inStreptomycesspecies. Sequential targeted gene manipulation involved in polyketide biosynthetic reguation synergistically provided an efficient and rational strategy forStreptomycesstrain improvement. Moreover, the engineered regulation-optimizedStreptomycesmutant strain was further used as a surrogate host for heterologous expression of polyketide pathway.
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Xu, Xin, Chengtuo Niu, Chunfeng Liu, Jinjing Wang, Feiyun Zheng, and Qi Li. "A Novel Approach to Develop Lager Yeast with Higher NADH Availability to Improve the Flavor Stability of Industrial Beer." Foods 10, no. 12 (December 8, 2021): 3057. http://dx.doi.org/10.3390/foods10123057.
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Flavor stability is important for beer quality and extensive efforts have been undertaken to improve this. In our previous work, we proved a concept whereby metabolic engineering lager yeast with increased cellular nicotinamide adenine dinucleotide hydride (NADH) availability could enhance the flavor stability of beer. However, the method for breeding non-genetically modified strains with higher NADH levels remains unsolved. In the current study, we reported a novel approach to develop such strains based on atmospheric and room temperature plasma (ARTP) mutagenesis coupled with 2,4-dinitrophenol (DNP) selection. As a result, we obtained a serial of strains with higher NADH levels as well as improved flavor stability. For screening an optimal strain with industrial application potential, we examined the other fermentation characteristics of the mutants and ultimately obtained the optimal strain, YDR-63. The overall fermentation performance of the strain YDR-63 in pilot-scale fermentation was similar to that of the parental strain YJ-002, but the acetaldehyde production was decreased by 53.7% and the resistance staling value of beer was improved by 99.8%. The forced beer aging assay further demonstrated that the favor stability was indeed improved as the contents of 5-hydroxymethylfurfural in YDR-63 was less than that in YJ-002 and the sensory notes of staling was weaker in YDR-63. We also employed this novel approach to another industrial strain, M14, and succeeded in improving its flavor stability. All the findings demonstrated the efficiency and versatility of this new approach in developing strains with improved flavor stability for the beer industry.
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Panke, Sven. "Taming the Beast of Biology: Synthetic Biology and Biological Systems Engineering." CHIMIA International Journal for Chemistry 74, no. 5 (May 27, 2020): 402–6. http://dx.doi.org/10.2533/chimia.2020.402.
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Despite the availability of a variety of ' -omics ' technologies to support the system-wide analysis of industrially relevant microorganisms, the manipulation of strains towards an economically relevant goal remains a challenge. Remarkably, our ability to catalogue the participants in and model ever more comprehensive aspects of a microorganism's physiology is now complemented by technologies that permanently expand the scope of engineering interventions that can be imagined. In fact, genome-wide editing and re-synthesis of microbial and even eukaryotic chromosomes have become widely applied methods. At the heart of this emerging system-wide engineering approach, often labelled ' Synthetic Biology ' , is the continuous improvement of large-scale DNA synthesis, which is put to two-fold use: (i) starting ever more ambitious efforts to re-write existing and coding novel molecular systems, and (ii) designing and constructing increasingly sophisticated library technologies, which has led to a renaissance of directed evolution in strain engineering. Here, we briefly review some of the critical concepts and technological stepping-stones of Synthetic Biology on its way to becoming a mature industrial technology.
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Gurusamy, Muralimohan, and Balkrishna C. Rao. "A Comprehensive Review of Large-Strain-Extrusion Machining Process for Production of Fine-Grained Materials." Crystals 13, no. 1 (January 11, 2023): 131. http://dx.doi.org/10.3390/cryst13010131.
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Bulk nanostructured metals and alloys are finding increasing structural applications due to their superior mechanical properties. The methods that rely on the severe plastic deformation technique for effecting microstructural refinement through imposing large strains are utilized mostly to produce nanostructured materials. The machining process has been demonstrated as a simple process for severe plastic deformation by imposing large strains through a single pass of the cutting tool where strains in a range of 1–15 can be imposed for a variety of materials by varying the cutting conditions and tool geometry. However, the geometry of the resulting chip subjected to severe plastic deformation during the machining process is not under control and, hence, a variant of the machining process, called the large-strain-extrusion machining process, has been proposed and utilized extensively for producing bulk nanostructured materials. Large-strain-extrusion machining possesses simultaneous control over microstructure refinement, through managing the strain during large-strain machining, and the shape and dimension of the resulting chip by the extrusion process. This study provides a comprehensive review of the large-strain-extrusion machining process by presenting the findings related to the utilization of this process for the production of fine-grained foils for various metals and alloys. Further research efforts related to finite-element modelling of large-strain-extrusion machining and their usefulness in designing the experimental setup and process conditions are also discussed.
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Bushman, Mary, and Rustom Antia. "A general framework for modelling the impact of co-infections on pathogen evolution." Journal of The Royal Society Interface 16, no. 155 (June 2019): 20190165. http://dx.doi.org/10.1098/rsif.2019.0165.
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Theoretical models suggest that mixed-strain infections, or co-infections, are an important driver of pathogen evolution. However, the within-host dynamics of co-infections vary enormously, which complicates efforts to develop a general understanding of how co-infections affect evolution. Here, we develop a general framework which condenses the within-host dynamics of co-infections into a few key outcomes, the most important of which is the overall R 0 of the co-infection. Similar to how fitness is determined by two different alleles in a heterozygote, the R 0 of a co-infection is a product of the R 0 values of the co-infecting strains, shaped by the interaction of those strains at the within-host level. Extending the analogy, we propose that the overall R 0 reflects the dominance of the co-infecting strains, and that the ability of a mutant strain to invade a population is a function of its dominance in co-infections. To illustrate the utility of these concepts, we use a within-host model to show how dominance arises from the within-host dynamics of a co-infection, and then use an epidemiological model to demonstrate that dominance is a robust predictor of the ability of a mutant strain to save a maladapted wild-type strain from extinction (evolutionary emergence).
Dissertations / Theses on the topic "Strain engineering efforts"
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Baby, Florent. "Contribution à l'identification et la prise en compte du comportement en traction des BFUP à l'échelle de la structure." Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00702129.
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Les Bétons Fibrés à Ultra hautes Performances (BFUP) se caractérisent par une résistance en compression bien supérieure à celle des BTHP couverts par la normalisation, une excellente durabilité et l'emploi d'un assez fort taux de fibres métalliques modifiant le recours habituel aux armatures. Ils sont notamment marqués par une résistance à la traction élevée. Cependant, selon le pourcentage volumique et le(s) type(s) de fibres initialement prévus dans la formulation et l'orientation réelle des fibres dans la structure vis-à-vis des directions principales de traction, leur comportement en traction peut être adoucissant ou écrouissant. Ces deux comportements nécessitent une approche différente pour assurer la sécurité du dimensionnement. Dans un premier temps, des méthodes de caractérisation du comportement en traction des BFUP ont été mises au point de manière à déterminer quel comportement va se mettre en place pour un BFUP et un élément structurel donné, en s'appuyant sur l'essai de flexion quatre points réalisé sur éprouvette non-entaillée. Cet essai nécessite l'utilisation d'une analyse inverse afin d'obtenir la loi de comportement " contrainte-déformation " (dans le cas d'un BFUP écrouissant en traction directe) ou " contrainte-ouverture de fissure " (dans le cas d'un BFUP adoucissant en traction directe). La configuration de l'essai de flexion quatre points pouvant entraîner des artefacts, elle nécessite un raccordement avec l'essai de traction directe. Pour valider ce raccordement, une méthode d'essai permettant de tester des corps d'épreuve de dimensions identiques en flexion et en traction directe a été mise au point. Les résultats de l'analyse inverse des essais de flexion ont été comparés à ceux des essais de traction directe. La comparaison a notamment permis de démontrer la robustesse des méthodes d'analyse proposées en particulier vis-à-vis de la cohérence de la discrimination écrouissant/adoucissant à partir du relevé de fissures sur chaque éprouvette. Dans un second temps, des méthodes de calcul adaptées à une approche type " contrainte - ouverture de fissure " ou " contrainte - déformation " ont été testées ou développées afin de prédire la résistance ou le comportement des poutres en BFUP soumises à des sollicitations concomitantes de flexion et d'effort tranchant. Cette configuration de sollicitation fait en effet intervenir de façon critique le comportement en traction du matériau. Pour valider ces méthodes de calculs, onze poutres en BFUP armé ou précontraint, avec ou sans armatures transversales et avec ou sans fibres (métalliques ou organiques) ont été testées sous une configuration de flexion conduisant à une rupture par effort tranchant. La caractérisation simultanée du comportement mécanique des BFUP à l'échelle du matériau en prenant en compte l'orientation réelle des fibres au sein des poutres, qui constitue une originalité de ce programme, s'est avérée particulièrement importante pour constater l'interaction entre le matériau, la géométrie de la structure et le procédé de mise en œuvre du BFUP sur l'orientation des fibres. Les méthodes d'analyse des essais de flexion quatre points mises au point ont permis d'évaluer quantitativement l'influence de la structure sur les paramètres caractérisant le comportement en traction du BFUP, notamment la déformation correspondant à la localisation de la fissure et marquant la fin du comportement global " pseudo-plastique ". Les conditions de synergie d'éventuelles armatures transversales et du BFUP vis-à-vis de la résistance à l'effort tranchant, ont pu être mises en évidence. Pour étendre l'analyse, la capacité de l'approche en " contrainte - ouverture de fissure " à prédire la résistance de poutres soumises à des sollicitations concomitantes de flexion et d'effort tranchant a été testée. L'approche en " contrainte - déformation " a également été appliquée, contribuant au développement et à la validation de méthodes élastoplastiques adaptées aux BFUP
Book chapters on the topic "Strain engineering efforts"
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Cucinotta, Filippo, Marcello Raffaele, and Fabio Salmeri. "A Topology Optimization Method for Stochastic Lattice Structures." In Lecture Notes in Mechanical Engineering, 235–40. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70566-4_38.
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AbstractStochastic lattice structures are very powerful solutions for filling three-dimensional spaces using a generative algorithm. They are suitable for 3D printing and are well appropriate to structural optimization and mass distribution, allowing for high-performance and low-weight structures. The paper shows a method, developed in the Rhino-Grasshopper environment, to distribute lattice structures until a goal is achieved, e.g. the reduction of the weight, the harmonization of the stresses or the limitation of the strain. As case study, a cantilever beam made of Titan alloy, by means of SLS technology has been optimized. The results of the work show the potentiality of the methodology, with a very performing structure and low computational efforts.
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Miralbes, R., D. Ranz, and D. Zouzias. "Study of the Use of Sawdust and Mycelium Composite as a Substitute of EPS." In Lecture Notes in Mechanical Engineering, 67–72. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70566-4_12.
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AbstractExpanded polystyrene foams are a petroleum-origin material that is usually used in some applications such as motorcyclist helmets. Despite it notably mechanical properties, it low density and its capability to absorb energy during an impact, it is necessary to find a renewable-origin substitute material. Thus, it has been studied the use of a sawdust and mycelium composite material under quasi-static and dynamic efforts. Sawdust is a waste material that has very small grains that are totally disaggregated so it has very low material properties. The use of oyster mushroom mycelium generates an internal structure that joins grains and, consequently, the resultant material has notably high mechanical properties. Then it has been compared the resultant properties (stress-strain curve, absorbed energy, decelerations, etc.) with the different densities EPS ones and it has been concluded that this composite material, despite it high density, it could be a suitable substitute material and in some cases it has better properties.
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Staber, Brian, and Johann Guilleminot. "Advances in the Stochastic Modeling of Constitutive Laws at Small and Finite Strains." In Advances in Computers and Information in Engineering Research, Volume 2, 53–77. ASME, 2021. http://dx.doi.org/10.1115/1.862025_ch3.
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The characterization and identification of uncertainties in the physical properties of complex materials have been the subjects of longstanding interest in both research and engineering. These efforts were supported by the growing interest in Uncertainty Quantification (UQ) where predominating system-parameter and model-form uncertainties are integrated in a unified mathematical treatment to endow predictions with some statistical measure of uncertainty (fidelity) [7] (see also [23, 30]). Once properly modeled and calibrated, these uncertainties can then be propagated to the structural response, following for instance the spectral approach introduced in the celebrated monograph by Ghanem and Spanos [8] (see also [13]). Such stochastic simulations are then purposely used in order to increase the robustness of the computational models and design procedures, especially when the mechanical models are highly nonlinear (in which case small variations in the inputs can have dramatic effects on the predicted outputs and thus, on design procedures). They also enable a deeper understanding of the critical mechanisms governing the physics (associated with damage propagation, for instance) at relevant scales.
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Lamb, Chris. "Prospects for Engineering Enhanced Durable Disease Resistance in Crops." In Feeding a World Population of More Than Eight Billion People. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195113129.003.0020.
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Plants have evolved a battery of defense mechanisms that in aggregate provide protection against a wide range of potential viral, bacterial, fungal, and other pathogens encountered throughout the plant life cycle. However, in the artificial setting of agriculture, disease, although the exception, can be costly and even devastating. Crop diseases have played significant roles in human history, exemplified by the widespread starvation and mass emigration triggered by the failure of European potato crops in the mid-nineteenth century as a result of late blight. Today, the use of pesticides, breeding for resistance, and integrated pest management provide important tools for reducing crop losses to pre-and postharvest diseases. However, agrichemicals are expensive, prohibitively so for many fanners in developing countries, and there are increasing concerns about environmental load from their intensive application. Likewise, major disease resistance (R) genes are in many cases not durable, resistance breaking down within one or two seasons as a result of selection pressure on the pathogen population, and most breeding efforts now rely on combinations of minor resistance genes, each giving partial protection. For a number of important diseases, such as take-all of wheat, there is no effective genetic resistance. Population growth, migration to cities, desertification, and climate change all now contribute to an urgent need to secure diversified food production against disease losses. In this chapter I discuss the prospects that genetic engineering of disease-resistance mechanisms can contribute to durable, broad protection and hence underpin enhanced crop productivity. Plants have a number of performed physical and chemical defensive mechanisms that help protect against the myriad potential pathogens to which plants arc exposed (Osbourn, 1996). However, superimposed upon this preexisting protective armory, plants respond to the perception of pathogen attack by activation of inducible defense mechanisms (Lamb et al., 1989; Staskawicz et al., 1995). Many of the most important crop diseases involve specialized interactions between pathogen and host. Interactions between specific plant cultivars and defined physiological races or strains of potential pathogens are described as compatible (host susceptible, pathogen virulent) or incompatible (host resistant, pathogen avirulent).
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Deamer, David W. "Prospects for Life on Other Planets." In Assembling Life. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780190646387.003.0017.
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This book describes a hypothetical process in which populations of protocells can spontaneously assemble and begin to grow and proliferate by energy- dependent polymerization. This might seem to be just an academic question pursued by a few dozen researchers as a matter of curiosity, but in the past three decades advances in engineering have reached a point where both NASA and the European Space Agency (ESA) routinely send spacecraft to other planetary objects in our solar system. A major question being pursued is whether life has emerged elsewhere than on Earth. The limited funds available to support such missions require decisions to be made about target priorities that are guided by judgment calls. These in turn depend on plausible scenarios related to the origin of life on habitable planetary surfaces. We know that other planetary bodies in our solar system have had or do have conditions that would permit microbial life to exist and perhaps even to begin. By a remarkable coincidence, the two most promising objects for extraterrestrial life happen to represent the two alternative scenarios described in this book: An origin of life in conditions of hydrothermal vents or an origin in hydrothermal fields. This final chapter will explore how these alternative views can guide our judgment about where to send future space missions designed as life-detection missions. Questions to be addressed: What is meant by habitability? Which planetary bodies are plausible sites for the origin of life? How do the hypotheses described in this book relate to those sites? There is healthy public interest in how life begins and whether it exists elsewhere in our solar system or on the myriad exoplanets now known to orbit other stars. This has fueled a series of films, television programs, and science fiction novels. Most of these feature extrapolations to intelligent life but a few, such as The Andromeda Strain, explore what might happen if a pathogenic organism from space began to spread to the human population. There is a serious and sustained scientific effort—SETI, or Search for Extraterrestrial Intelligence—devoted to finding an answer to this question.
Conference papers on the topic "Strain engineering efforts"
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Vaz, Bruno F., Rafael A. L. e Silva, and Auteliano A. S. Junior. "Measuring Stress and Strain Fields in Connecting Rods Using Laser Interferometry (ESPI)." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-63936.
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The understanding of how mechanical stresses influence in the behavior of automotive components is of great interest to the automotive industry. The design of products must be performed considering these efforts, always aiming to ensure smooth operation and no failures. To learn more about these efforts, numerical simulation can be done. However, the results obtained from these simulations must be confirmed by carrying out physical experiments. Many methods are available to obtain the stress/strain fields of the object been tested, among which the best known and widespread is the use of strain-gauges. This technique requires a relatively long time of preparation as well as several measurement places to obtain the full stress/strain field. The laser interferometry technique, on the other hand, reduces considerably the testing time to obtain the full stress/strain field, and no intervention on the object is required. This work aims to present a methodology for measuring stress/strain fields in connecting rods using an Electronic Speckle Pattern Interferometry (ESPI) device. In this work we will focus on obtaining the stresses in a flat surface of the rod. The region corresponds to the inner portion of the rod body, excluding only the edges of it that are slightly higher. In this region it’s easier to obtain the stress and strain fields than in the whole rod, which has many non-planar regions with a relatively complex geometry, especially near the ends. To plan the experiments, an experimental design was developed, based mainly on the concepts of Design of Experiments — DOE, to eliminate or at least reduce the influence of the noise over the results. The tests were performed with a forged connecting rod from a local manufacturing, which was submitted to compressive efforts. Finally we present the results of the measurements of the stress and strain fields obtained by the ESPI technique.
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Shang, Wanru, and Yingtao Liu. "Strain Sensing Using Hybrid Nanocomposite Membrane." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-67646.
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Damage and load sensing is rapidly advancing as driven by vast applications in aerospace and mechanical structures. Recently significant amount of efforts have been reported to develop new piezo-resistive strain sensor made from polymers with carbon nanoparticles, such as carbon nanotubes, carbon nanofibers, and graphene. These nanoparticles with advanced mechanical, electrical, and thermal properties are recognized as potential materials which can enhance mechanical performance and provide beneficial functionalities in polymers and composites. However, most previous research focused on the improvement of material properties for sensing applications. Limited work balanced the sensor design and material innovation for real time strain sensing. In this paper nanocomposite membranes are proposed to accurately measure local strain, especially for the strain sensing and health monitoring in composites. The micro-scale morphology and structures are first experimentally characterized. Both the fabrication process and the nanoparticle concentration are investigated to obtain the optimal sensing capabilities. The sensing function is achieved by correlating the piezoresistance variations to the stress or strain applied on the sensing area. Due to the conductive network formed and the tunneling resistance change in neighboring nanoparticles, the electrical resistance measured will show a clear correlation with the load conditions. The characterized membrane structures have the potential to be further applied to continuously monitor impact loads, especially focusing on low velocity barely visible damage in composites.
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Eckert, Chad E., and Michael S. Sacks. "A Strain Energy-Based Constitutive Model for Continuous-Fiber Tissue Engineered Valved Conduit Tissue." In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53967.
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Understanding growth and remodeling of extracelluar matrix (ECM) embedded in a scaffold phase is crucial for improving tissue engineering efforts, especially within the context of a mechanically-demanding enviroment to which engineered heart valve tissues (EHVT) are subjected. Our previous modeling efforts at short in vitro timepoints (one to three weeks) [1] illustrated the strong dependency of ECM-scaffold composite mechanical properties on that of the existing continuous scaffold phase. In this work, we build on these efforts by developing a generalized, large-deformation continuum-based model for short timepoint in vitro/in vivo environments and validating it using a ECM-analog system to simulate remodeling tissue. It is our intent to estimate the ECM mechanical quality from the measured scaffold-ECM composite.
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Kibey, Sandeep, Xiangyu Wang, Karel Minnaar, Mario L. Macia, Doug P. Fairchild, Wan C. Kan, Steve J. Ford, and Brian Newbury. "Tensile Strain Capacity Equations for Strain-Based Design of Welded Pipelines." In 2010 8th International Pipeline Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ipc2010-31661.
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Various industry efforts are underway to improve or develop new methods to address the design of pipelines in harsh arctic or seismically active regions. Reliable characterization of tensile strain capacity of welded pipelines is a key issue in development of strain-based design methodologies. Recently, improved FEA-based approaches for prediction of tensile strain capacity have been developed. However, these FEA-based approaches require complex, computationally intensive modeling and analyses. Parametric studies can provide an approach towards developing practical, efficient methods for strain capacity prediction. This paper presents closed-form, simplified strain capacity equations developed through a large-scale 3D FEA-based parametric study for welded pipelines. A non-dimensional parameter is presented to relate the influence of flaw and pipe geometry parameters to tensile strain capacity. The required input parameters, their limits of applicability and simplified equations for tensile strain capacity are presented. The equations are validated through a comprehensive full-scale test program to measure the strain capacity of pressurized pipelines spanning a range of pipe grades, thickness, weld overmatch and misalignment levels. It is shown that the current simplified equations can be used for appropriate specification of weld and pipe materials properties, design concept selection and the design of full-scale tests for strain-based design qualification. The equations can also provide the basis for codified strain-based design engineering critical assessment procedures for welded pipelines.
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Ohnishi, Masato, Ken Suzuki, and Hideo Miura. "Effect of Anisotropic Strain Field on the Electronic Conductance of Carbon Nanotubes." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64487.
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Since carbon nanotubes (CNTs) have unique electronic and mechanical properties, there have been many efforts to develop CNTs-based electronic devices and sensors. The authors have also validated the possibility of a highly sensitive strain sensor using popular resin in which multi-walled CNTs (MWNTs) were dispersed uniformly. It is, however, indispensable for clarifying how to change the electronic state of a deformed CNT for assuring the stable performance of the sensor because the reported sensitivity has ranged widely. In this study, the relationship between the deformation characteristic of a CNT under strain and its electronic properties was analyzed. The analysis result obtained from density functional theory (DFT) calculation showed that the orbital hybridization was occurred when the maximum local dihedral angle exceeded 10–20° and 25–30° in GNRs and CNTs, respectively, which induced the band gap.
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Noecker, Fredrick F., Doug Fairchild, Mike Cook, Mario Macia, and Wan Kan. "A Case Study in High Strain Capacity Pipeline Qualification: PNG LNG Project." In 2014 10th International Pipeline Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/ipc2014-33550.
Full textAbstract:
The onshore pipeline portion of the Papua New Guinea Liquefied Natural Gas (PNG LNG) project traverses terrain with seismically active faults with potential ground displacements up to four meters. The resulting longitudinal strain demand exceeds 0.5% strain, thereby requiring use of strain-based pipeline design (SBD) technology. This paper discusses the application of previously developed strain-based design methodologies to successfully qualify the PNG LNG pipeline system for a design tensile strain demand up to 3%, and flexibility to increase the design strain demand with additional restrictions on key variables impacting strain capacity at select locations. Key SBD pipeline qualification activities are discussed along with the required project timeline. The first activity is specifying, evaluating and procuring line pipe suitable for strain-based design. SBD line pipe must be strain-age resistant, have excellent longitudinal uniform elongation, and have tightly controlled ultimate tensile strength (UTS) limits to ensure robust girth weld overmatch. The girth welds must exhibit upper shelf fracture toughness, excellent tearing resistance, and have sufficient tensile strength to ensure adequate girth weld strength overmatch. The pipeline qualification effort culminates in full scale pipe strain testing as proof of performance. The specimens for these tests are fabricated with project-specific pipe, girth welds, and pipe fit-up (hi-lo misalignment). The girth welds contain machined flaws in both weld metals and heat affected zones, these flaws being sized consistent with acceptable flaw sizes predicted from analytical models and prior experience. The results of these tests and their significance are described. Efforts to reduce capacity through lowering strain demand are outlined, along with examples of construction challenges the project has successfully faced. Key engineering and project decisions, and lessons learned from this qualification effort are also detailed.
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Nesaei, Sepehr, Todd Letcher, and Fereidoon Delfanian. "Applying an Energy-Based Fatigue Life Prediction Method to Unnotched and Notched Al6061-T6 Specimen." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64485.
Full textAbstract:
There is a strong relationship between fracture mechanics and fatigue. Recently, an energy-based fatigue life prediction method has been studied as a method to quickly, but still accurately determine an SN curve for new materials. In the development of this energy-based fatigue life prediction theory, efforts have concentrated on monitoring stress/strain hysteresis loops only to make life predictions. Thus far, no attempts have been made to link knowledge of fracture mechanics to advances in the energy-based fatigue lifing theory. In this study, notched and unnotched AL6061-T6 flat specimens were fatigued with fatigue monitored by an extensometer. In order to prevent from buckling during hysteresis strain loops, R = −0.5 stress ratio was used. In addition, efforts will concentrate in the low cycle fatigue (LCF) region to support future works on monitoring crack length in fracture mechanics investigation. The goal of this study is to understand how specimens behave in the context of the energy-based fatigue life theory when notches/cracks are present.
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Ohnishi, Masato, Hiroshi Kawakami, Yusuke Suzuki, Ken Suzuki, and Hideo Miura. "Anisotropic Strain-Field-Induced Change of the Electronic Conductivity of Graphene Sheets and Carbon Nanotubes." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-87347.
Full textAbstract:
Since the discovery of carbon nanotubes (CNTs), there have been many efforts to develop various electronic devices and sensors. The authors have also validated the possibility of a highly sensitive strain sensor using popular resin in which multi-walled CNTs (MWNTs) were dispersed uniformly. It is, however, indispensable for clarifying how to change the electronic state of a deformed CNT for assuring the stable performance of the sensor because the reported sensitivity has ranged widely. In this study, the relationship between the deformation characteristic of a CNT under strain and its electronic conductivity was analyzed quantitatively. The analysis result obtained from density functional theory (DFT) calculation showed that the orbital hybridization was occured when the local curvature exceeded about 0.3 Å−1, inducing the decrease in the band gap. Based on the analytical results, a two-dimensional strain sensor was developed by applying buckling deformation-induced conductivity change of MWNTs by using MEMS technology.
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Alexander, Chris, Alexander Aalders, William Bath, Brent Vyvial, Rhett Dotson, and Danny Seal. "Evaluating Anchor Impact Damage to the Subsea Canyon Chief Pipeline Using Analysis and Full-Scale Testing Methods." In 2012 9th International Pipeline Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ipc2012-90578.
Full textAbstract:
This paper presents findings from a study conducted as part of a joint industry effort involving engineers from Williams Midstream, Stress Engineering Services, Inc., GL Noble Denton, and Saipem America. The purpose of this study was to evaluate the severity of damage inflicted to Williams’ subsea 18-inch × 0.875-inch, Grade X60 Canyon Chief Gas Export Pipeline due to an anchor impact at a water depth of 2,300 feet. The phases of work included an initial assessment after the damage to the deepwater pipeline was detected, evaluating localized damage via finite element analysis based using in-line inspection data, full-scale destructive testing including burst tests, and final efforts included the design and evaluation of a subsea-deployed repair sleeve. The study included modeling Saipem’s repair sleeve design accompanied by full-scale destructive testing. Strain gages were used to measure strain in the reinforced dent beneath the sleeve, that were then compared to prior results for the unrepaired dent test results. The work associated with this study represents one of the more comprehensive efforts conducted to date in evaluating damage to a subsea pipeline. The results of the analysis and testing work provided Williams with a solid understanding on the behavior on the damage inflected to the pipeline and what level of performance can be expected from the repaired pipeline during future operation. After the engineering analysis and testing phases of this work were completed, the deepwater pipeline was repaired.
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Bhate, D., D. Chan, G. Subbarayan, T. C. Chiu, V. Gupta, and D. Edwards. "Constitutive Behavior of Sn3.8Ag0.7Cu and Sn1.0Ag0.5Cu Alloys at Creep and Low Strain Rate Regimes." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-44151.
Full textAbstract:
Constitutive models for SnAgCu solder alloys are of great interest at the present. Commonly, constitutive models that have been successfully used in the past for Sn-Pb solders are used to describe the behavior of SnAgCu solder alloys. Two issues in the modeling of lead-free solders demand careful attention: (i) Lead-free solders show significantly different creep strain evolution with time, stress and temperature, and the assumption of evolution to steady state creep nearly instantaneously may not be valid in SnAgCu alloys and (ii) Models derived from bulk sample test data may not be reliable when predicting deformation behavior at the solder interconnection level for lead-free solders due to the differences in the inherent microstructures at these different scales. In addition, the building of valid constitutive models from test data derived from tests on solder joints must deconvolute the effects of joint geometry and its influence on stress heterogeneity. Such issues have often received insufficient attention in prior constitutive modeling efforts. In this study all of the above issues are addressed in developing constitutive models of Sn3.8Ag0.7Cu and Sn1.0Ag0.5Cu solder alloys, which represent the extremes of Ag composition that have been mooted at the present time. The results of monotonic testing are reported for strain rates ranging from 4.02E-6 to 2.40E-3 s−1. The creep behavior at stress levels ranging from 7.8 to 52 MPa are also described. Both types of tests were performed at temperatures of 25°C, 75°C and 125°C. The popular Anand model and the classical time-hardening creep model are fit to the data and the experimentally obtained model parameters are reported. The test data are compared against other reported data in the literature and conclusions are drawn on the plausible sources of error in the data reported in the prior literature.
Reports on the topic "Strain engineering efforts"
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Gaugler, Randy, Itamar Glazer, Daniel Segal, and Sarwar Hashmi. Molecular Approach for Improving the Stability of Insecticidal Nematodes. United States Department of Agriculture, November 2002. http://dx.doi.org/10.32747/2002.7580680.bard.
Full textAbstract:
Our overall goal is to improve insecticidal nematodes by genetically engineering strains capable of entering an enhanced state of dormancy that provides improved stability. Objectives: 1. Clone and sequence tps-l homologue from Steinernema carpocapsae. (Revised: A failure to isolate the tps gene group from Steinernema precipitated a redirection to identifying other genes involved in insecticidal nematode desiccation process.) 2. Incorporate cloned tps-l gene into S. carpocapsae to obtain overexpression, thereby, enhancing desiccation tolerance. (Revised: Other stress genes in addition to tps-l genes were cloned and efforts at expression in S. carpocapsae were conducted) 3. Characterize the transgenic strains. No other biological control agent offers more impressive attributes than insecticidal nematodes. However, their potential is limited by the bane of nearly all biological control agents: poor stability. This leads to inadequate shelf-life and ultimately reduced field efficacy. Nematode storage is based on desiccation, yet insecticidal species are only capable of partial desiccation termed quiescent anhydrobiosis. Overwhelming evidence has shown that when the disaccharide compound trehalose is elevated in anhydrobiotic organisms such as yeast, plants, and nematodes it enables these organisms the ability to survive environmental stresses i.e., desiccation. Armed with this information our goal was to improve insecticidal nematodes stability by engineering trehalose overexpression.